Conventionally, in the storage system, data is redundantly stored by plural pieces of information storing apparatus in order to avoid suspension of operations. For example, an information processing apparatus can make a data writing request to all of the plural pieces of information storing apparatus and make a data reading request to all of the plural pieces of information storing apparatus.
As a related art, for example, there is a technique in which a clock list is updated by a definite clock value calculated from the minimum logical clock value, the minimum definite clock value included in the clock list is identified as a definite clock value, and the clock list is transmitted to another piece of node apparatus. Furthermore, for example, there is a technique in which data consistency is managed in association with plural pieces of apparatus by using part of serialized synchronous metadata as a clock vector and defining the clock vector as the vector of the version. Moreover, there is a technique in which the order relationship among plural programs is analyzed by calculating order values. As related-art documents, there are Japanese Laid-open Patent Publication No. 2011-154631, Japanese National Publication of International Patent Application No. 2012-501586, and Japanese Laid-open Patent Publication No. 2009-20823.